#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdlib.h>
#include <stdio.h>

char *ecvt(double x, int n, int *dp, int *sign)
{
    static char buf[16];
    char tmp[32];
    int i, j;

    if (n-1U >= 15) n = 15;
    sprintf(tmp, "%.*e", n-1, x);
    i = *sign = (tmp[0]=='-');
    for (j=0; tmp[i]!='e'; j+=(tmp[i++]!='.'))
        buf[j] = tmp[i];
    buf[j] = 0;
    *dp = atoi(tmp+i+1)+1;

    return buf;
}
